1. Field of the Invention
Described herein are methods of binding nucleic acids having repeating elements and compositions, particularly γPNA (gamma peptide nucleic acid) compositions, useful in carrying out those methods.
2. Description of the Related Art
For most organisms, the genetic information is encoded in double-stranded DNA in the form of Watson-Crick base-pairing—in which adenine (A) pairs with thymine (T) and cytosine (C) with guanine (G). Depending on which set of this genetic information is decoded through transcription and translation, the developmental program and physiological status will be determined. Development of molecules that can be tailor-designed to bind sequence-specifically to any part of this genetic biopolymer, thereby enabling the control of the flow of genetic information and assessment and manipulation of the genome's structures and functions, is important for biological and biomedical research in the effort to unravel the molecular basis of life, including molecular tools for basic research in biology. This effort is also important for medicinal and therapeutic applications for the treatment and detection of genetic diseases.
Compared to proteins, RNA molecules are easier to target because they are made up of just four building blocks (A, C, G, U), whose interactions are defined by the well-established rules of Watson-Crick base-pairing. Compared to standard, double-stranded DNA (or RNA), the secondary structures of RNA are generally thermodynamically less stable and, thus, energetically less demanding for binding because, in addition to being canonical (perfectly-matched) base-pairs, many of them are noncanonical (mismatched) and contain single-stranded loops, bulges, and junctions. The presence of these local interacting domains is essential for ‘tertiary’ interactions and assembly of the secondary structures into compact three-dimensional shapes. As such, slight variations in the interaction patterns or bonding strengths within these regions will have a profound effect on the overall three-dimensional folding patterns of RNA. Thus, molecules that can be used to modulate RNA interactions and thereby interfere with the RNA folding behaviors are important as molecular tools for assessing RNA functions, as well as therapeutic and diagnostic reagents.
RNA-RNA and RNA-protein interactions play key roles in gene regulation, including replication, translation, folding and packaging. The ability to selectively bind to these perturbed regions within the secondary structures of RNA is important in manipulating their physiological functions.